Production of alkenylthiophenes



- Patented Jan 19,1954

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smaonncnamier etxam rmornmes I t "Hermafii-Pines and Bruno iiiietinsliai chicagq, I

1N0 Drawing; athanmumi1)1ewinnerr l 1 I w s r rNo. 1335422 Thismvention relates. to aprocess .ior 'prbflucing lalkenylthiol h nes and particularly Jo gp'roduc'ing abutenylthiophenef I An dbiect vof fthis 'inverition iis. tolihrbfluce:an v alkenylthiophene; k f v w. sLAndth'er o'bjec't oflthisinvenfion is to produce a "butenyl'thiophene.

A ;further lob'iect {of this invention is .to produce (2 -thienyl) -'2-butene; v a One. specific embodiment ofithisjinvention relates to a process 'for pr ducing. lanjalkenylthio- ,phene which comprises chloroalkyla'itin'gxgai'thiophene witha chloroeolefin to form a chloroalkylthiophenaiiand dehydrochlorinating said j 'chloroalkylthiophene ..to form .an. .ialkenylthi'oiphene.

i Another embodiment of this invention relates to a process for producing 'butenylthicphene which comprises chloroalkylating thiophene with methallyil clilor-ideto iorm chlorotertiarybutylthiop'hene'and dehydrochlorinating said chlorotertiarybutylthiophene to for-m qbutenylthiophene. v

A still furtherembodimen't "of-this invention relate'szto a process for producing (2-thienylie2- butenev which comprises reacting Ethiophene with metha'llyl chloride the presence of azmoron fluoride-iethylether catalyst zto. ft'orm chlorotertiarybutylthiopheneand ereacting lsaid chlorotertiarybutylthiophene with sodium hydroxide solution and recovering enyl)-2-butene. y

We have found that alkenylthiophenesand particularly butenylthiophenes can be"- obtained by the following sequence of steps, namely (1) chloroalkylation of thiophene in the presence of an acideacting alkylating catalyst and (2) dehydrochlorination of the resultant chloroalkyl- V-thiophene to forman alkenylthiophene. The two steps of this process are illustrated by the following equations which show the production of (2-thienyl) -2-butene by the reaction of methallyl chloride with thiophene itself to form chlorotertiarybutylthiophene which is then reacted with aqueous sodium hydroxide solution to remove hydrogen chloride and yield butenylthiophene in which the carbon atom of the substituent group rearranges to a stable butenyl radical.

cs Mom 7 above equations The chloroalkylation' "step carried out by comminglingathiophene, a haloolefin and a suitable catalyst such as boron triiiuoritie etii ylether air alltane:stilfonicacid; etc. eit- 'ait-ftentperatuie lfl frbmlabout to-about 100? c. and at a pressure.bfi from substantially atmospheric 'aucut 'l no'fiajtm'ospheres'r'or :a time H a .l -to about'iloinours-izo"produce -=a chi'oro'fllylated thiophene. time it resultant crcaikylated iatmcphenewhen separated converted starting materials;and byhe reaction ttei which-'itzis ere- V .fsealed moelauer with zanxaqueous alkaline solution such as an aqueous solution containing from about 1 to about 35% by weight of sodium hydroxide at a temperature of from about 100 to about 300 C. under pressure for a time of from about 0.5 to about 8 hours to effect dehydrochlorination and the production of a thiophene containing an alkenyl substituent.

The nature of the present invention and the type of results obtained thereby are illustrated further by the following examples which should not be misconstrued'to impose undue limitations upon the generally broad scope of the invention.

EXAMPLE I 226 grams of thiophene (2.7 moles) and 226 grams of methallyl chloride (2.5 moles) were placed in a glass reactor of one liter capacity and 68 grams of a boron trifluoride-ethylether catalyst was added thereto with stirring. The reaction mixture. was maintained at a temperature of 80 C. for a time of 2.7 hours after which 56 the reaction products were subjected to washing bit 72the;. process is t butylthiophene and 125 cc. of anaqueous solution containing by weight of sodium hydroxide were placed in a glass-lined rotating autoclave of 850 cc; capacity and maintained at a. temperature of 200 for a time of 4 hours. The resultant reaction products were then washed, dried, and distilled, to separate fractions with the boiling ranges andproperties given in the following table.

Table I Flask Vapor I Distillate Fraction Temper- Temper- At mm. Number ature, ature, Hg

0. 0. cc. gr. m,"

HPEPNI" voocoooo Fraction V-3 did not react with sodium, gave a negative test for halogen but reacted immediately with potassium permanganate solution thus indicating unsaturation.

' Analysis of this material showed it to have the composition expected for (2-thienyl)-2f-butene. The analysis was:

Calcd. for CaHmS: c, 69.57; H, 7.25; s, 23.19. Found: C, 69.06; H, 7.56; s,23.54.1

EXAIVIPLEII of methallyl chloride which reacted.

EXAMPLE m 82 grams or bromothiophene (0.5 mole) and 0.25 mole of methallyl chloride were reacted in the presence of 15 grams of a boron fluorideethylether catalyst at a temperature of 66 C. :for a time of 2 hours. About 80% of the methallyl chloride was recovered unchanged. 5- chloro-t-butyl-2-bromothiophene was recovered in a yield of about 60% based upon the weight We claim as our invention:

1. A process for producing (Z-thienyl) -2- 'butene which comprises reacting chlorotertiarybutylthiophene with an alkali to efiect dehydrochlorination.

2; A process for producing (2-thienyD-2- butene which comprises reacting chlorotertiarybutylthiophene with sodium hydroxide solution and recovering the resultant (2-thi'enyD-2- butene. I

' 3. A process for producing (Z-thienyD-Z- butene which comprises reacting 'chlorotertiarybutylthiophene with. an aqueous alkaline solution containing from about 1% to about 35% by weight of sodium hydroxide at. a temperature of from about to about 300 C. under pressure for a time of from about 0.5 to about 8 hours.

4. A process for producing (Z-thienyll-Z- buten which comprises reacting chlorotertiarybutylthiophene with an alkali at a temperature of from about 100 to about 300 C. to eiTect dehydrochlorination.

5. A process for producing (2thienyl)-2- butene which comprises reacting chlorotertiarybutylthiophene with sodium hydroxide solution at a temperature of from about 100 to about 300 C. and recovering the resultant (Z-thienyl) 2-butene.

HERMAN PINES. BRUNO KVETINSKAS.

"References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,141,611 Malishev Dec. 27, 1938 2,492,663 Schick Dec. 27, 1949 2,556,419 Emerson June 12, 1951 OTHER REFERENCES Weygand, Organic Preparations, pp. 316-317, Interscience Publ, New York, 1945. 

1. A PROCESS FOR PRODUCING (2-THIENYL)-2BUTENE WHICH COMPRISES REACTING CHLOROTERTIARYBUTYLTHIOPHENE WITH AN ALKALI TO EFFECT DEHYDROCHLORINATION. 